This invention relates to an automotive seat belt retractor assembly and particularly to one useful for passive restraint systems of the type in which the retractor is mounted in the vehicle door.
In accordance with Federal Motor Vehicle Safety Standards (FMVSS) many passenger motor vehicles will soon be required to have passive restraint systems for front seat occupants. Such restraint systems provide impact protection without requiring the occupant to take steps to deploy the system. One type of passive restraint system is a so-called "automatic" seat belt. These systems position seat belt webbing across the occupant as they enter the vehicle so that the separate step of attaching a buckle fastener is unnecessary. In one type of automatic seat belt system, one or more seat belt retractors are mounted inside the vehicle door with one end of the webbing connected to an anchorage at the in-board side of the occupant seat. As the vehicle door is opened, the webbing spools out from the door mounted retractor, and becomes retracted when the door is closed.
Many modern day seat belt retractors are described as emergency locking retractor (ELR) types since they allow the webbing to be readily spooled out thus providing comfort and convenience for the occupants, but becomes locked to inhibit webbing payout when the vehicle is exposed to a deceleration force above a predetermined threshold. Typical ELR devices include a pendulum type inertia sensor.
In applications where a passive seat belt retractor with the emergency locking feature is mounted in the door, a means for locking out the inertia sensitive device is necessary to prevent the retractor from inhibiting payout of webbing upon opening of the door.
Modern day seat belt retractors are frequently also provided with a so-called "comfort" mechanism which prevents the retractor from constantly exerting a retracting force on the belt webbing which tends to be uncomfortable and annoying to occupants. The comfort mechanism includes a clutch or "window shade" type mechanism which allows the retractor to introduce slack in the webbing when the vehicle is being operated. These systems typically sense belt movement so that changes in direction of belt movement of certain magnitudes trigger the comfort mechanism to engage, and becomes cancelled by thereafter withdrawing the webbing. For in-door retractor applications, the comfort feature must be cancelled to allow the webbing to be retracted as the door is being closed. Engagement of the comfort feature in such situations could cause loose webbing to be closed into the door opening.
In view of the foregoing, there is a need to provide door mounted retractors of the type having emergency locking and comfort latching capabilities with a mechanism for rendering these systems inoperative during door opening and closing. In one prior art system, a mechanical door position sensing lever or button is provided which is mounted to the door and detects opening of the door. Movement of the sensing mechanism is communicated to the retractor through a mechanical cable. Although such systems generally perform satisfactorily, they have disadvantages in terms of their high cost and reliability. Accordingly, there is a need to provide an improved retractor operating mechanism of the above type.
The improved passive seat belt retractor assembly in accordance with this invention achieves the above mentioned desirable features through the use of an electrical solenoid actuated retractor operating mechanism. A door position switch is employed to energize the solenoid whenever the door is opened which serves to prevent engagement of the inertia sensitive lock mechanism and further cancels the comfort latching system while the door is open. As a means of reducing the size and cost of the actuation solenoid of the retractor, this invention uses a latching mechanism which causes a latch plate to become "cocked" during normal operation such that the solenoid merely serves to release the cocked latch plate which requires only a minimal force output.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.